The US vice presidential candidates are set to clash in their sole debate, with Democrats itching for revenge after Mitt Romney's drubbing of President Barack Obama tightened the White House race.
After Obama's lackluster performance last week, Vice President Joe Biden, 69, was expected to mount a full-throated attack against the surging Romney ticket on Thursday, while striving to avoid the gaffes the veteran politician is famous for.
He will face the much younger Representative Paul Ryan, 42, whose controversial government-slashing budget made him a hero among conservatives but who has never debated on a national stage.
The vice presidential debate rarely elicits much excitement, but this year all eyes will be on Danville, Kentucky to see whether Biden can stem Romney's sharp rise in the polls over recent days.
Obama tried to steady panicking supporters on Wednesday, insisting he would win re-election despite a "bad night" in which he had been "too polite" to Romney.
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"I got this," Obama said in a radio interview, predicting that Democratic "hand-wringing" over his limp performance would be a mere memory after his next clash with Romney on Tuesday.
Obama's campaign team meanwhile launched a new assault on the resurgent Republican nominee less than four weeks before the election, accusing him of hiding "extreme" stances to win support in the vital political centre ground.
Romney for his part scampered across Ohio, packing in three events on Wednesday in the battleground state that has never been lost by a successful Republican candidate and is shaping up to be the epicentre of this year's election.
The state has lost thousands of blue-collar jobs abroad, so Romney was on fertile political ground as he warned China's economy was gaining fast on America and accused Obama of "laxity" on enforcing free trade rules.
Obama's campaign accused Romney of peddling "head-spinning falsehoods" and suggested the former venture capitalist had swelled his fortune by investing in Chinese firms guilty of pirating US intellectual copyrights.
Democrats also tried to snare Romney in a culture war, after he told the Des Moines Register newspaper in Iowa that he would not introduce any legislation as president restricting the right to abortion.
Democrats scented a cover-up, as Romney has said he would appoint Supreme Court judges who oppose the procedure.
"We know that the real Mitt Romney will say anything to win ... he is cynically hiding his positions," said Obama's deputy campaign manager Stephanie Cutter.
Romney later suggested his statements were not contradictory because he would use the presidency's executive powers - instead of writing a bill - to halt government funds for foreign organisations that promote abortion.
"I'm a pro-life candidate. I'll be a pro-life president," he said.
Struggling for moderates
The Obama camp sees the abortion comments as a way to dent Romney's standing among women voters. Several polls show he improved among the crucial demographic after last week's first of a trio of debates with Obama.
Presidential candidates frequently move to the political centre to appeal to moderate voters once they have solidified support in their own party base.
But Romney spent months struggling to reassure his conservative base in a hard-fought primary and only truly began moderating his positions - on taxing the rich, immigration and health care - during last week's debate in Denver.
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Recent polls show an unsettled race, with some national polls - like Gallup's daily tracking survey which had Romney and Obama tied at 48 per cent - suggesting Romney's debate bounce was subsiding.
A Fox News poll had Romney up a single point. Obama had led the same poll by five points before the debate.
There was also movement towards Romney in state surveys that had the race in battlegrounds like Nevada, Florida, Nevada and Ohio within a few points.
The debate at Kentucky's Centre College will be moderated by ABC News foreign correspondent Martha Raddatz and will begin at 9:00pm local time (01:00 GMT Friday).